Weights are one of the few measurements where Americans and the rest of the world rarely share a unit. Grocery labels, shipping quotes, bathroom scales and lab reports switch between grams, kilograms, ounces, pounds, stone and several kinds of ton. This converter handles all of them with the exact definitions that link the US customary and metric systems, and breaks results into the mixed forms people actually say, like “11 stone 11” or “165 pounds 5 ounces.”
How to use the weight converter
- Type the weight in Value.
- Choose its unit in From and the unit you want in To.
- The tape shows the converted value, the conversion factor in both directions, and the same weight as pounds and ounces and as stone and pounds.
- The table below lists the weight in all 18 supported units, including troy units for precious metals.
Weight conversion formula
Each unit is defined as an exact number of kilograms, so conversion is one multiplication:
The key definition is 1 lb = 0.45359237 kg exactly, adopted in 1959 by the United States, the United Kingdom, Canada, Australia, New Zealand and South Africa. Every other customary unit follows from it: an ounce is 1/16 lb (28.349523125 g), a stone is 14 lb, a short ton is 2,000 lb and a grain is 1/7,000 lb.
Worked example: 75 kilograms
75 kg × 2.20462262 = 165.3467 lb
Pounds and ounces: 0.3467 lb × 16 = 5.5 oz, so 75 kg ≈ 165 lb 5.5 oz.
Stone and pounds: 165.3467 ÷ 14 = 11.81 st, and 0.81 × 14 ≈ 11.3 lb, so 75 kg ≈ 11 st 11.3 lb.
Going the other way, 185 lb × 0.45359237 = 83.91 kg.
Common weight conversions
| From | To | Multiply by |
|---|---|---|
| kilograms | pounds | 2.2046226 |
| pounds | kilograms | 0.45359237 (exact) |
| ounces | grams | 28.349523125 (exact) |
| grams | ounces | 0.03527396 |
| stone | kilograms | 6.35029318 (exact) |
| short tons | kilograms | 907.18474 (exact) |
| metric tonnes | pounds | 2,204.6226 |
| long tons | kilograms | 1,016.0469088 (exact) |
| carats | milligrams | 200 (exact) |
Three kinds of ton
The word “ton” causes more shipping and engineering mix-ups than any other weight unit:
- Short ton (US): 2,000 lb. Used for US freight, coal, gravel and vehicle ratings.
- Long ton (UK): 2,240 lb, or 20 hundredweight of 112 lb. Still used for ship displacement.
- Metric ton (tonne): 1,000 kg. Used in international trade and science.
A difference of 12% between a short ton and a long ton is large enough to matter on any invoice, so always confirm which one is meant.
Mass, weight and the pound
In physics, the kilogram measures mass, while weight is a force measured in newtons. The pound plays both roles in everyday American usage, which is why engineers distinguish the pound-mass (lb) from the pound-force (lbf). Bathroom and kitchen scales actually sense force but are calibrated so that they display mass under standard gravity, 9.80665 m/s². For converting a force reading, use the force converter, and to find what an object weighs on another planet, try the weight calculator.
Specialized weight systems
Two older English systems survive alongside the metric one. Avoirdupois units (ounce, pound, stone, hundredweight) cover almost everything sold by weight; the avoirdupois weight converter covers drams and quarters too. Troy units (troy ounce, pennyweight, troy pound) are used only for precious metals and are handled in detail by the troy weight converter. Gemstones use the metric carat of exactly 200 mg.
Frequently asked questions
How many pounds are in a kilogram?
One kilogram is 2.20462262 pounds. The exact definition runs the other way: one pound is exactly 0.45359237 kg, fixed by the international yard and pound agreement of 1959.
What is the difference between a ton and a tonne?
A US short ton is 2,000 lb (907.18 kg). A British long ton is 2,240 lb (1,016.05 kg). A metric tonne is 1,000 kg, or about 2,204.6 lb, so it sits between the other two.
Is weight the same as mass?
Not strictly. Mass is the amount of matter, measured in kilograms or pounds; weight is the force gravity exerts on it. On Earth the two are used interchangeably because scales are calibrated for Earth's gravity, but an astronaut on the Moon keeps the same mass and weighs about one sixth as much.
How many ounces are in a pound?
Sixteen ordinary (avoirdupois) ounces make a pound. Precious metals use troy weight instead, where 12 troy ounces make a troy pound.
How heavy is a stone?
A stone is exactly 14 pounds, or 6.35029318 kg. It is still the everyday unit for body weight in the UK and Ireland, so 185 lb is written as 13 st 3 lb.